
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
.h2 {
    font-weight: 400;
}
    </style>
</head>
<body>
    <h2 class="h2">不想变粗
    </h2>
    
</body>
</html>